Power and fuel efficiency of a gas turbine engine are a function of the inlet temperature of the combustion gases to the turbine which is generally maximized consistent with turbine and nozzle structural integrity. For example, the maximum turbine rotor inlet temperature exhibited in current state-of-the-art uncooled metal turbine rotors is approximately 2000.degree. F. Increasing the turbine rotor inlet temperature above 2000.degree. F. requires the use of advanced super alloy blade materials which are generally not compatible with the mechanical properties of the rotor disk.
A solution to this incompatibility problem is to adopt a dual-property approach to the fabrication of the turbine rotor. In large gas turbines, where size and complexity constraints are not acute, this is accomplished by using discrete blades of a high rupture strength material mechanically attached to a high burst strength disk. However, the physical size, cost, and complexity associated with this dual-property rotor concept have precluded its use in small, lightweight gas turbine engines.